Rufinamide is chemically, 1-[(2,6-Difluorophenyl)methyl]-1H-1,2,3-triazole-4-carboxamide and has the structural formula:

Rufinamide is an anticonvulsant medication. It is used in combination with other medication and therapy to treat Lennox-Gastaut syndrome and various other seizure disorders. It is marketed under the brand name Banzel® by EISAI INC.
Rufinamide and its process were disclosed in European patent no. 199262.
Polymorphism is defined as “the ability of a substance to exist as two or more crystalline phases that have different arrangement and/or conformations of the molecules in the crystal Lattice. Thus, in the strict sense, polymorphs are different crystalline structures of the same pure substance in which the molecules have different arrangements and/or different configurations of the molecules”. Different polymorphs may differ in their physical properties such as melting point, solubility, X-ray diffraction patterns, etc. Although those differences disappear once the compound is dissolved, they can appreciably influence pharmaceutically relevant properties of the solid form, such as handling properties, dissolution rate and stability. Such properties can significantly influence the processing, shelf life, and commercial acceptance of a polymorph. It is therefore important to investigate all solid forms of a drug, including all polymorphic forms, and to determine the stability, dissolution and flow properties of each polymorphic form. Polymorphic forms of a compound can be distinguished in the laboratory by analytical methods such as X-ray diffraction (XRD), Differential Scanning calorimetry (DSC) and Infrared spectrometry (IR).
Solvent medium and mode of crystallization play very important role in obtaining one polymorphic Form over the other.
Rufinamide can exist in different polymorphic Forms, which may differ from each other in terms of stability, physical properties, spectral data and methods of preparation.
U.S. Pat. No. 6,740,669 disclosed crystal modification A and A′ of rufinamide.
European patent no. 0994864 disclosed crystal modification B and C of rufinamide.
Form α and β of rufinamide were disclosed in European patent application no. 2292609 ('609 patent). According to the '609 patent, Form α can be characterized by the 2θ values at 4.5, 9.0, 13.5, 18.0, 18.8, 19.5, 20.6, 24.6, 25.7, 26.5, 27.4, 27.9, 28.7, 30.0 and 31.8±0.2 degrees.
According to the '609 patent, Form β can be characterized by the 2θ values at 6.4, 12.7, 17.7, 18.5, 19.1, 22.2, 22.8, 24.2, 26.5, 28.9, 29.4, 32.1 and 34.3±0.2 degrees.
International patent application publication no. WO 2011/135105 disclosed crystalline Form R-5 of rufinamide.
We have found a solid dispersion of rufinamide in combination with a pharmaceutically acceptable carrier. The solid dispersion of rufinamide is stable, reproducible and amicable for large scale preparation.
Thus, an object of the present invention is to provide a solid dispersion of rufinamide in combination with a pharmaceutically acceptable carrier, process for its preparation and pharmaceutical compositions comprising it.